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1
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Synchrotron White Beam Topographic Studies of Gallium Arsenide Crystals

100%
Wierzchowski W., Wieteska K., Graeff W.
Acta Physica Polonica A
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1997
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vol. 91
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issue 5
1015-1019
EN
A series of samples cut out from different types of gallium arsenide crystals with low dislocation density were studied by means of white beam synchrotron topography. The investigation was performed with transmission and back-reflection projection methods and transmission section method. Some of the topographs in transmission geometry provided a very high sensitivity suitable for revealing small precipitates. The transmission section images significantly differed depending on the wavelength and absorption. In some cases a distinct Pendellösung fringes and fine details of dislocation and precipitates images were observed. It was possible to reproduce the character of these images by means of numerical simulation based on integration of Takagi-Taupin equations. Due to more convenient choice of radiation, synchrotron back-reflection projection topography provided much better visibility of dislocations than analogous methods realized with conventional X-ray sources.
2
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Interference Fringes in Synchrotron Section Topography of Implanted Silicon with a Very Large Ion Range

100%
Wieteska K., Wierzchowski W., Graeff W., Dłużewska K.
Acta Physica Polonica A
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1997
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vol. 91
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issue 5
1021-1024
EN
Silicon crystals implanted with 9 MeV protons to the dose of 5×10^{17} cm^{-2} were studied with X-ray topographic methods using both conventional and synchrotron radiation sources. After the implantation the crystals were thermally and electron annealed. The implantation produced large 600 μm thick shot-through layer while the total thickness of the samples was 1.6 mm. It was confirmed by means of double crystal topography that the whole crystal was elastically bent. The transmission section patterns revealed both parts of the implanted crystal separated by strong contrasts coming from the most damaged layer and distinct interference fringes which appeared on one side of the topograph only. The location of the fringes changed when the beam entered the other side of the sample. The mechanism of fringe formation was studied with numerical integration of the Takagi-Taupin equations, especially studying the intensity distribution in the diffraction plane. The simulations reproduced the location of the fringes in different geometries and indicate that they can be caused both by variable crystal curvature and variable ion dose.
3
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White Beam Synchrotron Topographic Characterisation of Silicon Wafers Directly Bonded by Oxide Layer

88%
Wierzchowski W., Wieteska K., Graeff W., Gawlik G., Pawłowska M.
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vol. 96
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issue 2
283-288
EN
Various types of layer structures obtained by direct bonding of oxidised silicon wafers were studied by means of different X-ray topographic methods using white synchrotron beam and the observation of selective etching pattern using scanning electron microscopy and optical microscopy with Nomarski contrast. In the present investigation the particularly important results were obtained with synchrotron section topography, which revealed different defects caused by bonding of thick wafers, in particular the dislocations and microcracks. The different situation was observed in the case of bonding with a very thin layer separated from a silicon substrate by high dose proton implantation. In this case a thin layer accommodated practically all induced strain and the bonded oxidised thick substrate remained defect-free in its inner volume.
4
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Lattice Deformation in Al_{x}Ga_{1-x}As Epitaxial Layers Caused by Implantation with High Doses of 1 Mev Si Ions

88%
Wieteska K., Wierzchowski W., Graeff W., Turos A., Grötzschel R.
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vol. 96
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issue 2
289-293
EN
A series of highly perfect Al_{0.45}Ga_{0.55} As epitaxial layers implanted with 1 MeV Si ions to the doses in a range 7×10^{13}-2×10^{15} ions/cm^{2} were studied with various conventional and synchrotron X-ray diffraction methods. The presently used methods allowed both the measurement of lattice parameter changes and strain induced deformation. The evaluation of complete strain profiles was also performed by numerical simulation of diffraction curves. It was found that the implantation induced considerable change of lattice parameter reached the maximum at the dose 3×10^{14} ions/cm^{2}. The recorded curves proved also that the lattice parameter is almost constant in the near surface region of the implanted layers. The applied doses did not cause lattice amorphisation at room temperature.
5
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Investigation of Misfit Dislocation Sources in GaAs Epitaxial Layers

88%
Wierzchowski W., Mazur K., Strupiński W., Wieteska K., Graeff W.
Acta Physica Polonica A
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1996
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vol. 89
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issue 3
341-346
EN
The formation of misfit dislocation was studied in GaAs homoepitaxial layers on the substrates containing considerable amount of isoelectronic indium. The layers were grown with metal-oxide chemical vapour deposition and chemical vapour deposition methods including low temperature process with tertiarbutylarsine arsenic source. The critical conditions of misfit dislocation formation were exceeded up to 5×. The samples were examined before and after epitaxial process with a number of different X-ray topographic and diffractometric methods, including high resolution synchrotron white beam topography. The crystallographic identification of the defects was supported by the numerical simulation of topographic images. It was found that a number of threading dislocations, continuing in the epitaxial layer from those existing in the substrate, did not take part in the formation of misfit dislocations despite a suitable slip system. On the other hand, the formation of misfit dislocations from small imperfections of epitaxial deposit was proved in many cases. A reasonable good quality of the layers was confirmed by the resolution of individual defects and only small broadening of rocking curves.
6
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Investigation of Lattice Strains in Layered Structures Containing Porous Silicon

88%
Wierzchowski W., Wieteska K., Graeff W., Brzozowski A., Nossarzewska-Orłowska E.
Acta Physica Polonica A
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2002
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vol. 102
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issue 2
283-288
EN
Silicon layered structures containing porous silicon modified with various thermal treatments and epitaxial layers deposited on porous layers were studied with a number of complementary X-ray diffraction methods using synchrotron source. The methods of characterisation included recording of rocking curves for reflections with various asymmetry as well as projection, section and micro-Laue topography. It was found that oxidising and sintering of porous silicon seriously modified the strains in the porous layer and in some cases even inverting the sense of strain with respect to that in initially formed porous layer. Consequently the deposited epitaxial layer usually was not laterally coherent with the substrate. Some of the investigated layers were not stable in time and after few months period exhibited significant lost of coherence of porous skeleton.
7
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Interference Fringes in the Plane Wave Topographic Images of Growth Bands in Si:Ge

88%
Wieteska K., Wierzchowski W., Graeff W., Lefeld-Sosnowska M., Regulska M.
Acta Physica Polonica A
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2002
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vol. 101
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issue 5
729-734
EN
An Si:Ge crystal with approximately 3% of germanium was studied with strongly collimated short-wavelength monochromatic synchrotron beam (beamline E2 at HASYLAB). The topographs obtained in the asymmetric 224 reflection revealed the presence of interference fringes related to growth bands caused by segregation of germanium. The fringes, observed for the first time, were strongly dependent on the angular setting and it was possible to distinguish at least three systems of fringes. A number of features of the existing strain field, which may be important for the formation of the fringes, was determined using other topographic methods, especially the Bragg-case section topography.
8
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X-Ray Topographic Studies of Defect Structure in YVO_4 Crystals

76%
Wieteska K., Wierzchowski W., Łukasiewicz T., Wierzbicka E., Malinowska A., Lefeld-Sosnowska M., Graeff W.
Acta Physica Polonica A
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2008
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vol. 114
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issue 2
455-461
EN
The perfection of YVO_4 crystals, which are predicted to replace formerly used YAG garnets due to higher quantum efficiency and lower excitation level, was studied. The investigations of Czochralski grown undoped YVO_4 single crystals were performed mainly by means of X-ray topographic methods. Both synchrotron and conventional X-ray sources were used. The study revealed relatively high density of weak point-like contrasts which can be most probably interpreted as dislocation outcrops. In regions of the crystal close to its boundary we observed glide bands. It was also found that in some regions the dislocations form local subgrain boundaries. The white beam back reflection and monochromatic beam topography allowed to evaluate a local misorientation which not exceeded several angular minutes. No segregation fringes were observed proving a good homogeneity of chemical composition.
9
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Conventional and Synchrotron X-Ray Topography of Defects in the Core Region of SrLaGaO_4

76%
Malinowska A., Lefeld-Sosnowska M., Wieteska K., Wierzchowski W., Pajączkowska A., Graeff W.
Acta Physica Polonica A
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2008
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vol. 114
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issue 2
433-438
EN
SrLaGaO_4 single crystals are perspective substrate materials for high temperature superconductors thin films, elements of thermal radiation receivers and other electronic devices. The defect structure of the Czochralski grown SrLaGaO_4 crystal was investigated by means of X-ray topography exploring both conventional and synchrotron sources. The crystal lattice defects in the core region of the crystal were investigated. The regular network of defects arranged in rows only in ⟨100⟩ direction was observed. Owing to high resolution of synchrotron radiation white beam back reflection topographs one can distinguish individual spots forming the lines of the rows. It can be supposed that these elongated rod-like volume defects are located in 100 lattice planes forming a kind of walls. They are built approximately of the same phase as crystal but crystallize at a different moment than a rest of the crystal due to the constitutional supercooling.
10
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X-ray Synchrotron Studies of Nanostructure Formation in High Temperature - Pressure Treated Silicon Implanted with Hydrogen

76%
Wieteska K., Wierzchowski W., Graeff W., Misiuk A., Barcz A., Bryja L., Popov V.
Acta Physica Polonica A
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2002
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vol. 102
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issue 2
239-244
EN
The effects of various high temperature-pressure treatments in Czochralski grown silicon (Cz-Si) implanted with 130 keV hydrogen to the dose of 4times10^{16} cm^{-2} were investigated using synchrotron X-ray topographic methods and rocking curve measurements. The high temperature- pressure processes included 10 h annealing at 450°C, 650°C, and 725°C at argon pressure 12 kbar and 1 bar. The topographic investigations were performed with projection and section methods in back-reflection and transmission geometry. It was found that annealing resulted in significantly reduced strain induced by the implantation, which became undetectable with presently used very sensitive synchrotron arrangement. A significant difference between the Cz-Si:H samples annealed at high and atmospheric pressure was observed. In the first case a distinct topographic contrast attributed to the formation of comparatively larger inclusions was observed. This effect was different at different temperatures. The samples annealed at enhanced pressure were more uniform and often produced significant interference effects.
11
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Influence of SiC Surface Preparation on Homoepitaxial Growth; X-ray Reflectometric Studies

64%
Mazur K., Wierzchowski W., Wieteska K., Hofman W., Sakowska H., Kościewicz K., Strupiński W., Graeff W.
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issue 2
272-276
EN
X-ray reflectometric and diffraction topographic methods were applied for examination of 4H and 6H silicon carbide substrates finished with various regimes, as well as, silicon carbide epitaxial layers. The investigations indicated a very good quality of the substrate surfaces finished with the process established at the Institute of Electronic Materials Technology, which provided the surface roughness σ = 0.55 ± 0.07 nm for 4H-SiC wafers. These values were better than those of substrate wafers offered by many commercial producers. The surface roughness was decreased during the initial high temperature etching to σ = 0.22 ± 0.07 nm. A relatively good structural quality was confirmed in the case of 4H epitaxial wafers deposited on the substrates prepared from the crystals manufactured at the IEMT, with the 8° off-cut from the main (001) plane.
12
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X-ray Topographic Investigations of Domain Structure in Czochralski Grown Pr_{x}La_{1-x}AlO_{3} Crystals

64%
Wieteska K., Wierzchowski W., Malinowska A., Turczyński S., Lefeld-Sosnowska M., Pawlak D., Łukasiewicz T., Graeff W.
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issue 2
268-271
EN
In the present paper X-ray diffraction topographic techniques were applied to a number of samples cut from Czochralski grown Pr_{x}La_{1-x}AlO_{3} crystals with different ratio of praseodymium and lanthanum. Conventional and synchrotron X-ray topographic investigations revealed differently developed domain structures dependent on the composition of mixed praseodymium lanthanum aluminium perovskites. Some large mosaic blocks were observed together with the domains. In the best crystals, X-ray topographs revealed striation fringes and individual dislocations inside large domains. Synchrotron topographs allowed us to indicate that the domains correspond to three different crystallographic planes, and to evaluate the lattice misorientation between domains in the range of 20-50 arc min.
13
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Defect Structure Formed at Different Stages οf Growth Process in Erbium, Calcium and Holmium Doped YVO_{4} Crystals

64%
Malinowska A., Wierzbicka E., Lefeld-Sosnowska M., Wieteska K., Wierzchowski W., Łukasiewicz T., Świrkowicz M., Graeff W.
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issue 2
328-331
EN
The defect structure of YVO_{4} single crystals doped with Er^{3+}, Ho^{3+} and Ca^{2+} were studied by X-ray diffraction topographic methods, using laboratory and synchrotron radiation sources. Variously developed block structure was the dominating imperfection of the investigated crystals observed both in conventional Lang and synchrotron topographs. The evaluation of block misorientation was realised by means of superimposed projection and section white beam synchrotron radiation topographs. More possibilities of following the mutual rotation of blocks were provided by means of white beam synchrotron radiation WBSR projection topographs exposed through the fine mesh.
14
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Revealing the Defects Introduced in N- or Ge-doped Cz-Si by γ Irradiation and High Temperature-High Pressure Treatment

52%
Wieteska K., Misiuk A., Prujszczyk M., Wierzchowski W., Surma B., Bąk-Misiuk J., Romanowski P., Shalimov A., Capan I., Yang D., Graeff W.
Acta Physica Polonica A
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2008
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vol. 114
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issue 2
439-446
EN
Effect of processing under high hydrostatic pressure (= 1.1 GPa), applied at 1270 K, on Czochralski grown silicon with interstitial oxygen content (c_O) up to 1.1×10^{18} cm^{-3}, admixed with N or Ge (Si-N, c_N ≤ 1.2×10^{15} cm^{-3}, or Si-Ge, c_{Ge} ≈ 7×10^{17} cm^{-3}, respectively), pre-annealed at up to 1400 K and next irradiated withγ-rays (dose, D up to 2530 Mrad, at energy E = 1.2 MeV), was investigated by high resolution X-ray diffraction, Fourier transform infrared spectroscopy, and synchrotron topography. Processing of γ-irradiated Si-N and Si-Ge under high pressure leads to stimulated precipitation of oxygen at the nucleation sites created by irradiation. It means that radiation history of Si-N and Si-Ge can be revealed by appropriate high temperature-high pressure processing.
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